The proposed study will investigate the role of maternal diet during pregnancy and early childhood diet in the etiology of a specific type of childhood brain cancer, primitive neuroectodermal tumor (PNET). The hypotheses to be tested are based on results from our previous study of PNET in which strong and significant protective effects of fruit, vegetable, vitamin C, and folate intake were observed. Multivitamin supplements early in pregnancy and iron supplements also appeared to decrease risk. This proposal intends to replicate and extend these findings in a methodologically more rigorous study. Maternal diet will be assessed comprehensively using a food frequency questionnaire that has been widely used and validated in several settings. Aspects of early childhood diet will also be studied as possible risk factors as well as possible effect modifiers or confounders of maternal diet. Two substudies will be conducted to investigate the validity and reproducibility of the food frequency questionnaire for reporting on diet during a pregnancy up to 11 years in the past. The findings of the substudies will be used in the interpretation of the dietary results. Another aim is to investigate the role of other suggested risk factors, including reproductive history, parental occupation, and farm residence. The study will use a case-control design and will include 400 cases and 400 matched controls. Cases will be children diagnosed with PNET before age 6 and registered with the Children's Cancer Group, one of two pediatric oncology clinical trials groups in the U.S. Controls will be selected by random-digit-dialing and matched to cases on age, race, and geographic area. Data on maternal diet, child diet, and other factors will be collected by telephone interview. Diet has been studied little in relation to childhood cancer. The proposed study will provide data on the role of maternal and child diet in the etiology of one histologic type of childhood cancer and will also contribute to the methodology of investigating pregnancy and early childhood diet retrospectively.